Science oriented after school enrichment programs are becoming commonplace in middle schools and high schools of the United States. Educators are realizing the importance of "hands on" activities as opposed to daily academic text book learning exercises involving extensive paper work only. Theoretical studies and computer simulations are no substitute for building and creating things with a persons own two hands. Prefabricated motor kits containing die cast or stamped parts and plastic molded parts are not only prohibitively expensive for most school budgets but introduce higher level manufacturing techniques which are not part of the subject being taught and therefore subtract from the hands on learning experience.
The motor and the motor or embodiments of this invention are made from simple, low technology, hardware store parts such as nails, magnets, threaded rod, tubing, nuts and washers and common household materials such as empty milk cartons and drinking water containers. The only tools required for construction are a hack saw, file, knife, scissors, glue gun, small crescent wrench and hand or electric drill.
The prior art incorporating the concept of total hands on construction of electric motors were simple wire loops in a permanent magnetic field. Usually the wire itself was the motor shaft and the bearings were paper clips taped to the side of Styrofoam cups. Commutation was accomplished by painting a stripe on a bare section of the wire motor shaft itself. The paper clips acted as the motor brushes. These Styrofoam cup DC motors had only one torque impulse per cycle. While these motors provide excellent instructional information on motor principles, they lack sufficient torque to drive science projects. Other variations of this same concept involving coils wrapped around match boxes have also been developed and published, however, these motors also lack sufficient torque to drive science and engineering projects.
The typical embodiment and alternate embodiments of this invention not only cover basic motor principles but the motors themselves can be used to provide power for class room engineering projects such as model race cars, planes, cranes, boats, robots, etc. The motors are completely reversible by simply changing polarity. The typical embodiment and alternate embodiments of this invention also are easily converted to low voltage alternating current (AC) electric motors by replacing the permanent field magnets with simple nail electromagnets and then connecting these field electromagnet wires in parallel with the motor brush terminals. Converting the motors of this invention to (AC) further enhances motor basic principle instruction. The instructional value of the motor of this invention and its embodiments can further be enhanced by rotating them at moderate speed. In this mode, the motors become, milli voltage generators.
Other educational electric motors, such as that shown in U.S. Pat. No. 4,127,785 by Noguchi, are excellent for instruction of motor principles and can be used, with appropriate equipment, to power class room engineering projects. The disadvantage is that this motor incorporates prefabricated parts which subtract from the total hands on creative process. Also parts for the Noguchi motor are not as readily available as are the simple parts of the typical motor and its embodiments of this invention. U.S. Pat. No. 3,678,310 by Munn et al. titled: "Instructional Electric Motor" has the same disadvantages namely premanufactured parts. The "Electric Motors for Toys" under U.S. Pat. No. 3,445,692 by Masao Kato also has the prefabricated parts and therefore the disadvantages as explained above. This motor may not, however, have been designed for motor instructional purposes other than that instruction that occurs from connecting the motor to a power train.
The kit motor by Logix Enterprises in their 1972 book titled "Science fun Experiments in Electricity" also incorporates complex premanufactured motor parts. For example, the armature pole pieces or armature plates are a lamination of special shaped pieces. The commutator consists of three complex shape segments each with a stem extension fitted into segment holders. Commutator segments are held in position by special lugs on the segments which fit into holes located in the segment holder. The field pole pieces are preformed steel bars. The ends of the threaded motor shaft are machined to provide smooth motor shaft extensions for insertion into bearing brackets. The motor by Logix Enterprises is excellent for instructional purposes, however, parts are not readily available at local hardware stores and parts cannot reasonably be made in a class room setting.
Commercially available preassembled small motors can be used for class room engineering projects but the electric motor principle is entirely absent. Also, commercial preassembled motors usually have small diameter, smooth hardened shaft extensions which are difficult to attach anything to. Small commercial motors require hot solder to connect the lead wires. Because of the hazardous nature of most solder and fluxes, particularly in the hands of middle school children, these motors should only be used under strict supervision. The typical embodiment and alternate embodiments of the motor under this invention require no soldering of any kind.
Other kit motors available from hobby stores or mail order houses usually have only three poles on the armature thus limiting their power and starting capability. Such kit motors usually have laminated parts which have been die cut. Also, these motors usually have extrusion molded plastic parts and preformed wrap-around permanent magnets. The armatures of most small commercial preassembled motors also contain only three poles and use the toy motor winding. Worse, the small commercial preassembled motors cannot be disassembled. The high technology used to manufacture either the preassembled commercial motors or the kit motors defeats the purpose of the enrichment programs which is to demonstrate basic electric motor principles and provide "hands on" construction using low technology and readily available materials. Also, these motors are usually prohibitively expensive for most public school budgets.